Electric switch



C; GRETER ELECTRIC SWITCH Jan. 19, 1932'.

Original Filed Oct. 29, 1928 In rental: fim f reter,

4H0? ey Patent ed Jan. 19, 1932 CARL GRETER, OF BERLIN -SCHONEBERG, GERMANY ELECTRIC SW'IT CH Application filed October 29, 1928, Serial No. 315,783, and in Germain" April 17, 1928.. Renewed September 19, 1931.

This invention comprises improvements in electric switches and is concerned with switches of the press-button type suitable for various switching purposes.

The principal object of this invention is to provide a press-button switch having a snap action for giving a quick make or a quick break, whereby deterioration of the I switch contacts is avoided.

A further object is to devise a switch of the character indicated which is economical to produce and of extremely simple construction in spite of the mechanism introduced for the snap action.

Yet another object is to construct a switch of the character indicated wherein the closed contacts remain in engagement during the pressing of the knob or button until the moment of release for the snap break action.

Finally, an object of the invention is to provide in a press-button switch a comblnation ofa torsional spring and circular action cam surfaces so designed and disposed as to co-operate for the bringing about of the desired snap action at a predetermined moment of release.

In order to enable the invention to be readi 1V understood a description of one example (if construction will be given with reference to the drawings accompanying and forming part of this specification, in which drawings:

Figure lis a central vertical section of a switch embodying these improvements, the section being taken on the line AB of Figure 3.

Figure 2 is an elevation of the internal parts of the switch, these being displayed by removal of one half of the cover or casing which is seen in vertical section on the line CD of Figure 3. 1

Figure 3 is a plan of the switch with the cover and press-button removed.

Figure 4 comprises two views. one being an elevation of the upper portion of the switch spindle and the other being a plan thereof.

Figure 5 is an iiwerted plan of the pressbutton.

Figure 6 is a sectional elevation of the cen tral portion of the movable switch member. Flgure 7 1s a developed diagrammatic view of interi'ial teeth within the central portion of the movable switch member.

The switch comprises cover or casing-a secured by screwing on a base 7), a press-butten 0 being depressible into the casing a with guidance forthe depression of the movable switch member d. A spindle e passing through the perforated centre of the member (l is detachably secured in the base I) which is made of porcelain or other insulating material. The means for detachably fixing the spindle e and holding it against revolution need not be described as they may be of any appropriate character.

The lower portion of the spindle e is of circular cross section and may be of smaller diameter than the upper portion which is formed with flats at diametrically opposite 0 points, the metal being removed to such an extent that the upper portion of the spindle 6 maybe said to be of approximately oblong cross section, as will be understood from Fig ures 3 and 4. At the junction between the upper and lower portions, the spindle e is formed with a flange or collar from which project four fingers or star points f. It desired, two fingers f'180 apart could be used in place of four disposed 90 apart as in Figures 3 and 4. The fingers f are bevelled along, one side as will be seen clearly from the end view of one of them in the elevation in Figures 1 and 4. The switch member d is freely revoluble around the lower portion of the spindle e and is pressed upwards against the collar of the star f by means of a spring q. The switch member 03 may be moulded as a disc of insulating material having mounted on its upper surface a ring g of metal, said ring having radial projections at diametrically opposite points on its periphery and such pro ections may constitute the contacts of the sliding member (1 for engagement with the fixed contacts hereinafter referred to.

In the centre of the upper surface of the member (I there is formed or fixed an upstanding hollow cylindrical part b which surrounds the upper portion of the spindle e and has an internal diameter large enough for enabling it to slide over the star member f. Onits interior surface the cylindrical part it is formed or fitted with four similar and uniformly spaced teeth 11 which are of triangular or ratchet tooth shape one edge being vertical and the other inclined. If the star member f has four points as shown, each of the teeth 71 will engage with one of the points of the star member, which will prevent the teeth '6 and\ therefore the cylindrical part and movable member (1 from rotating whilst such teeth remain in engagement.

On the exterior of the cylindrical part It there are formed or fixed four similar and uniformly spaced projections is each of which 1 projections m which, as will be seen from Figare 2, are similar in shape to the projections is but are inverted so that their inclined transverse edges come over the inclined top edges of the projections 0 as shown. The spring Z is adapted for acting torsionally as well as by compression against the button a and for this purpose its lower end is engaged with one point of the star member f Whilst its upper end is engaged in a small hole-o, Figure 5, formed in the lower end of the central part n of the press button 0. In the normal outward position of the ress button 0 shown in the drawing, the sprlng Z acting torsionally adjusts the button a circularly so that the projections m lie immediately over the projecs tions as shown in Figure 2. The central inner part n of the press button extends downwards to the spindle e and is formed with a bore 7; which in section or plan, as seen in'Figure 5, is of what may be called a double segmental shape. That is to say, the bore p is of-such a shape as to enable it to slide over the upper portion of the'spindle e which, in the example illustrated, is of a somewhat oblong cross section, the outer portions of the section of the bore p being enlarged so as to permit the part it and button 0 to be free to turn through a limited angle relatively to the spindle 6. This limited turning of the button is performed alternately with and against the torsional action of the spring Z and it will now be understood 'how the spindle e arrests the turning of the button so that the projections m lie directly above the projectionsla when the button 0 is in its outward position as already stated. The limited turning aforesaid is of such amplitude as to enable the. projections m to slip past the projections is in circumstances to be explained.

It will be noted from Figure 1 that the cylindrical wall of the button 0 extends downwards below the lower ends of the projections m and that the cylindrical part h of the member d extends upwardly abovethe upper ends of the projections 71. As the internal diameter of the button 0 is greater than the external diameter of the cylindrical part b; to the extent of about the thickness'of the projections m and 70 it will be understood that there is mutual guidance between the parts a and h during the sliding movements.

On the base 6 are the upstanding switch contactsr and 8, these contacts being blades fixed by terminal screws t and u and having upper vertical and lparallel.p'prtions which may be bent over at t e top to engage the projections of the conductor ring above described. Owing to the form and of these spring contacts r and a it is possible for the member d to descend for a certain distance without the breaking of contact between the rin g and the contacts r and 5 as will be clear ron'i Figure 1.

disposition Assuming the switch to be in the on condition asshown in the drawings and that it is desired to put it to the 01f condition, the

operation is as follows :The button 0 is depressed against the compression of the spring Z. As the projections-m and is are in vertical alignment, the depression of the button 0 will cause also the depression of the member ll, against the action of the spring 9. During the first part of the descent of the member d, the circuit will not be broken as the contact ring 9 will maintain contact with the blades 1' and s as above explained. During this rotion of the descent, the vertical edges 0 the teeth 13 slide against the points of the star f so that the member 01 cannot turn. When the member (1 has been depressed so far that the tips of the teeth z' descend below the star member f so that the teeth 2' are no longer engaged by the points of thestar f, the said member'd is then free to turn around the spindle e. At this moment, and owing to the continued depression of the button 0 against the action of the spring 9, the bevelled or inclined ends of the projections m and k will react against one another with a camming action and, seeing that the button 0 cannot turn owing to the engagement of the bore 72 with the upper portion of the spindle e, the member at will be forced to turn through a small pressure of the spring 9, theinclineol edges of the teeth 2' engage the points of the star member 7 so that the member d whilst rising to the position in which it is arrested is also causedto turn through a quarter of a revolution owing to the cam action between the teeth 2' and the points of the star. This rising movement and turning of the member d is practically instantaneous so that there is a quick break or snapaction in the removal of the projections of the ring 9 from contact with the contact blades 1* and 8. At the end of the rapid turning of the member d through a quarter of a revolution, due to the .inclined or helical edge of each of the teeth i extending around 90, each of the points of the star) wi ll be engaged by the vertical edge of the nextfollowing tooth 2' at the end of the movement and the member at will be arrested in a position 90removed from that shown in the drawings. As, at this instant, the button 0 is still depressed, it will be seen that the projections is on the cylindrical part h of themeinber (.5 will overtake the projections m of the button. In order that the coming together of the projections 70 and m shall not obstruct this full quarter turn of the member (Z, the longitudinal edges at the meeting sides-of such projections are inclined as aforesaid and as seen in Figure 2. Upon now releasing the press button 0. its work having been finished, the spring Zreturns the same to the outward position and during this ascent of the button the projections m will slide past the projections k and the said inclined edges of such projections will produce a cam action resulting in a limited turning of the button 0 relatively'to the spindle e and member (1. Owing to the ends of the spring Z being fixedly attached to the star 7 and part 'n of the button 0 respectively, the said spring'l will be stressed torsionally'by the turning of the button under the camming action of the projections m and k. Thus, immediately the button 0 reaches its uppermost or outermost position so that the projections m are clear of the projections k, the torque of the spring Zwill turn the button 0 back again to bring the projections m immediately over the projections is and the original-starting condition is restored. excepting that the switch is now in the ofl 'condition instead of the on condition.- It will be apparent, without detailed description. that if the button 0- is 'now again depressed, the member (I will per form a rapid movement from the off position back again to the on position shown in the drawings and that for each depression of the button 0 the member (I will perform such quarter revolution with snap action giving either a make or a break as the case may be.

It is to be understood that the details of construction may be varied without departing from the invention-as hereinafter claimed. Thus, for example, the construction and dis. position of switch contacts and other details may be modified and changed without afiecting the novel and advantageous switching predetermined rotation when said switch member is released, cam devices operative be- $5 tween, said button and said member to produce limited rotation of said member at the bottom of the depression, and-resilient means operative upon said member to resist depression thereof.

2. In a press button switch in which 'de-, pression of the button depresses a rotatable switch member against the resistance of resilient means, the combination of ratchetlike means operative between said member and a fixed abutment-device for preventing rotation of said switch member during-depression thereof and for producing rotation during ascent when released by said button,

and cumming means operativebetweeirsaid circular relation between said ratchet-like means and said abutn'ient device at the bottom of the depression. v

3. Press button switch comprising in combination a'hollow press button, a fixed spindle, a. switch member slidable upon and rotatable about said spindle, guide means operative for guiding said'button on said spindle and adapted for permitting limited rotation of said button relatively to said spindle combined abutment and cam devices upon said' button and upon said switch memb r said" devices being co-operative for depressing said member during the initial portion of the depression of said button and for subsequent- 1y releasing said member for snap action,-

and snap action mechanism operative upon devices on said member (o-operative with projectlons on said spmdlefor preventing turning of said member during depression and for producing pre-determined turning of said member during ascent thereof, other resilient means constantly resisting depression of-said switch member, and cam devices 011 said button operative to depress said member and to turn the latter through a limited angle at the bottom of a depression substantially as set forth.

5. Press button switch co-m n'ising a revoluble switch member adapted for depression by said button, fixedly mounted switch contacts adapted for preserving circuit connec- -tion with said member during the first part.

of said depression movement, snap action mechanism operative for rapidly revolving said member through a-pre-determined angle during the final part of said depression, and self-setting abutments on said button and switch member said abutments co-operating to effect depression of said member and final- .ly subsequently releasing said member for the snap action substantially as set forth.

6. Press button switch comprising in combination a hollow press button, a sleeve depending centrally from said button and having a shaped bore, a fixed central spindle having a shaped upper portion adapted for enabling said sleeve to slide longitudinally over it with ability to turn through a limited angle about said spindle, a star member disposed intermediately along the length of said spindle, a combined compression and torsion spring disposed between said sleeve and said star and having respective ends connected with said sleeve and said star, a switchmember slidable and revolubly mounted on the lower portion of said spindle, a spring coiled around the lower portion of said spindle and constantly tending to. elevate said switch member, spaced ratchet-like teeth on said switch member, normally in engagement with said star but disengageable therefrom at the bottom of a depression said teeth being adapted for imparting rectilinear guidance to said switch member during depression and rotational guidance during elevation,

cam shaped abutments on said button, and cam shaped abutments on said switch member, said abutments normally lying in vertical alignment and being operative for imparting depressionof said button to said switch member and said abutments being adapted for-slipping past one another at the bottom of a depression to release said switch member for ascent in a different circular position and forslipping past one another-during subsequent outward movement of said button whereby the first-named spring is torsioned for finally bringing said abutments into realignment substantially as set forth.

7. Press button switch comprising a depressible and rotatable switch member in combination with 'a rotary step-by-step feed mechanism including means for producing a 

